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Owing to the occupying tendency of Mn4+ at octahedral sites, doping Mn4+ activators in tetrahedral structures poses challenges and hence is seldom reported. In this work, tetrahedrally sited Mn4+ phosphors were studied. By combining X-ray diffraction (XRD) data with Rietveld refinement analysis, the location of Mn4+ was determined. It was found that by adding excessive raw MgO, the phosphor synthesis temperature can be improved, enhancing the crystallinity of the crystal and thus improving the emission performance of the phosphor. In addition, excessive raw MgO forms a second phase in an LMGO matrix, which does not change the doping site for Mn4+. The Tanabe–Sugano diagram of Mn4+ in the tetrahedral field and the energy-level diagram of these phosphors were constructed for the first time, and the excitation and emission mechanisms are discussed in detail. With 1.2-fold excess of raw MgO, the prepared sample (LMGO-Mn-1.2) shows the best luminescence, demonstrating red emissions peaked at 656 nm and affording an emission intensity enhancement of over 50 times compared to a stoichiometric LMGO:Mn4+ system. At 150 °C, LMGO-Mn-1.2 keeps 90% emission intensity compared to that at room temperature. Finally, a high-efficiency warm white light–emitting diode was built. This work provides new insights into the study of Mn4+-activated phosphors in a tetrahedron crystal field. [ABSTRACT FROM AUTHOR]

The tail rotor of a helicopter, a crucial component, traditionally relies on a complex drive mode involving reducers and transmission gears. This conventional setup, with its lengthy transmission chain and numerous components, hinders miniaturization efforts. In response to this challenge, our paper presents a novel piezoelectric drive approach. Our objective was to suggest an innovative design capable of minimizing the components involved in the tail rotor drive. This design can be adjusted in size according to specific requirements and is effective up to a specified speed. Moreover, it facilitates the process of miniaturization and integration. The piezoelectric actuator's stator comprises an ultrasonic amplitude transformer, a ring, and three drive teeth. Utilizing the rod-like structure of the tail brace, the actuator is simplified by adhering ceramic sheets to it. The rotary piezoelectric actuator combines the first longitudinal mode of a rod with torus bending modes. The drive teeth then amplify the ring's displacement, facilitating rotor rotation. The resonant frequency and modal shape of the actuator were determined using the finite element method. Furthermore, an investigation was conducted to analyze the influence of the drive teeth positioning on the motion trajectory at the contact point. Theoretically, we infer that the declination angle of the drive tooth is a crucial parameter for achieving high speeds. To test our idea, we built three prototype stators with different drive tooth declination angles. Our actuator stands out for its cost-effectiveness, structural simplicity, compatibility with harmonic signals, and ease of miniaturization. It can be considered for the drive of the tail rotor of a microhelicopter. [ABSTRACT FROM AUTHOR]

In order to improve the effective utilization of agricultural irrigation water and to reasonably allocate water resources in irrigation areas, it is necessary to use open channel flow measurement devices that are accurate and easy to carry. In this study, a spring-plate flow measurement device with different plate widths was designed. Through a combination of theoretical analysis and numerical simulation, the measurement characteristics of the device in specific channels under conditions of 20–105 m3/h flow were studied, the relationship between the flow rate and the force acting on the plate surface was fitted, and the hydraulic characteristics of water flow during its use, such as pressure, velocity distribution, and head loss, were analyzed. The results show that in the process of using the spring-plate flow measurement device, the force on the plate surface increases with the increase in the flow rate, and the force on the plate surface is related to the flow rate in the channel by a power of 5/6. The width of the measurement plate impacts the accuracy of flow measurement, and the smaller the plate width, the larger the error in flow measurement. The distribution of pressure on the measurement plate is similar to that of static pressure, and the pressure increases with the increase in the width of the measurement plate. The upstream flow velocity of the device is small, and the water level increases due to obstruction of the measurement plate. When it connects to the downstream water surface, the water level rapidly decreases, and the flow velocity increases. In using the spring-plate flow measurement device to measure flow, head loss will be produced, and the magnitude of this loss increases with the increase in the width of the measurement plate. The research results provide a theoretical basis for the application of spring plate flow-measuring devices in irrigation areas. [ABSTRACT FROM AUTHOR]

Piezo-driven resonant fiber optic scanners are gaining more and more attention due to their simple structure, weak electromagnetic radiation, and non-friction loss. Conventional piezo-driven resonant fiber optic scanners typically use quadrature piezoelectric tubes (piezo tubes) operating in 31-mode with high drive voltage and low excitation efficiency. In order to solve the abovementioned problem, a resonant fiber scanner driven by co-fired multilayer piezoelectric ceramics (CMPCs) is proposed in which four CMPCs drive a cantilevered fiber optic in the first-order bending mode to achieve efficient and fast space-filling scanning. In this paper, the cantilever beam vibration model with base displacement excitation was derived to provide a theoretical basis for the design of the fiber optic scanner. The finite element method was used to guide the dynamic design of the scanner. Finally, the dynamics characteristics and scanning trajectory of the prepared scanner prototype were tested and compared with the theoretical and simulation calculation results. Experimental results showed that the scanner can achieve three types of space-filling scanning: spiral, Lissajous, and propeller. Compared with the structure using piezo tubes, the designed scanner achieved the same scanning range with smaller axial dimensions, lower drive voltage, and higher efficiency. The scanner can achieve a free end displacement of 10 mm in both horizontal and vertical directions under a sinusoidal excitation signal of 50 Vp-p and 200 Hz. The theoretical, simulation and experimental results validate the feasibility of the proposed scanner structure and provide new ideas for the design of resonant fiber optic scanners. [ABSTRACT FROM AUTHOR]

Traveling wave rotary ultrasonic motors (TRUMs) are widely used in various industrial processes due to their attractive features, such as compact structure, high accuracy, and fast response. However, the major limiting factors of the operational performance of TRUMs under high-voltage excitation are the nonlinear behavior caused by the nonlinearities of the piezoelectric materials and the friction between the stator and rotor of the motor. In this study, a nonlinear dynamics model and an identification method are presented to directly design the driver circuit for suppressing the nonlinear behavior under high voltage excitation. Firstly, by studying the time–frequency characteristics of the isolated electrode voltage, a single-sided Hertzian contact forced oscillator model of TRUMs is established, involving the nonlinearities of the piezoelectric material and friction. Secondly, a harmonic balance nonlinear identification is proposed in the time domain for TRUMs. The influence of the voltage and preload on the nonlinear phenomena is discussed. Lastly, a novel driver circuit is proposed to suppress the nonlinearities using feedback from the isolated electrode. Experiments showed that the total harmonic distortion decreased by 89.4% under 500 Vpp. The proposed drive circuit design method is used to find a high excitation voltage and preload to achieve greater motor output power. [ABSTRACT FROM AUTHOR]

To meet the requirements of miniaturization, lightweight and precision of space optical instruments, an aperture driven by single-phase piezoelectric motor was designed. The whole structure of the apertures was designed to realize the integration of structure and function. Then, piezoelectric stators with high strength and power density were designed by using piezoelectric ceramics and carbon fiber composite materials. The dynamics characteristics of laminated piezoelectric stators were analyzed by COMSOL finite element software, and the modal frequency consistency was adjusted. The structure optimization and interference mode separation design of the moving rings of diaphragm were also completed. According to the design scheme, the prototype of piezoelectric apertures was manufactured. The mass is only 49 g, aperture range is in 0.5~35 mm.The experimental results show that the full opening and closing time of the apertures are as 89 ms and 92.4 ms respectively, and the minimum angular resolution is as 4x10-5 rad. This study simplifies the composition and control of the diaphragm, making it more compact in structures and smaller in weight while ensuring accuracy. [ABSTRACT FROM AUTHOR]

Polymer-based piezoelectric motors have excellent properties, such as lightweight and corrosion resistance. In addition, 3D printing and customized additive manufacturing of polymers provide new opportunities for the development of piezoelectric motors with complex or special structures. In this paper, a 3D printed polymer-based sandwich-type piezoelectric motor operating in a single longitudinal mode is developed. A vibration decomposition model of the motor and an analytical model considering polymer viscoelasticity are established to analyze the dynamic characteristics and to determine the geometric structure of the motor. To increase the coefficient of friction, a polymer surface texture is utilized on the contacts. The experimental results show that the friction coefficient of the contact tip with surface texture is about 0.16, which increased by 45.5% compared to a smooth surface. The resonance frequency is 28.648 kHz, and the maximum no-load speed under 300 Vp-p is 54 r/min. Our study shows the promise of polymer-based materials in the development of the piezoelectric motor. [ABSTRACT FROM AUTHOR]

In-plane bending traveling wave ultrasonic motors (USM), which are compact in structure and flexible in design, have been widely applied in biological engineering, optical engineering, and aerospace engineering. However, the high driving voltage and complicated driving circuit of this kind of USM restrict their further miniaturization and electromechanical integration in these applications and bring some potential safety hazards. To solve this problem, a low-voltage-driving traveling wave USM incorporating cofired multilayer piezoelectric ceramics was proposed in this work. Four cofired piezoelectric ceramics were strategically designed to excite two orthogonal third-order in-plane bending modes with the same frequency of the USM. The principles of traveling wave synthesis and low-voltage-driving of the USM were deduced, and the stator dynamic design and transient dynamic simulation were carried out by finite-element method. The microproperties of cofired piezoelectric multilayer ceramics, the vibration characteristics of the stator, and the mechanical output performance of the USM were tested by experiments. The results indicated that the motor can work as low as 5 $\text{V}_{\text {p-p}}$. A long stroke with a maximum forward and reverse rotational speeds of 187.7 and 176.6 r/min were obtained, respectively, and a maximum stalling torque of 4.8 mN $\cdot$ m at 47.3 kHz under 15 $\text{V}_{\text {p-p}}$ was achieved. The results showed that the proposed USM is small, low in driving voltage, and high in torque output, which has promising applications in aerospace, biomedicine, and other fields that require a lightweight and integration of driving devices. [ABSTRACT FROM AUTHOR]

Electronic scanning of two-dimensional (2-D) arrays and mechanical or freehand scanning of one-dimensional (1-D) arrays have been mostly utilized for conventional three-dimensional (3-D) ultrasound (US) imaging. However, the development of 2-D arrays and the hardware systems are complicated and expensive, while freehand systems with positioning sensors and mechanical systems are mostly bulky. This article represents a novel scanning strategy for achieving high-quality 3-D US imaging with a high-frequency single-element transducer. A 42-MHz US transducer with a compact structure was designed and fabricated, which was excited in the 2-D vibration by a tubular piezoelectric actuator. A dedicated imaging system was set up and both B-mode and 3-D US imaging of a custom wire phantom have been carried out to evaluate the performance of the proposed transducer. Compared to the results obtained with the motorized linear translation stage, the reconstructed images obtained by the proposed resonance scanning method are accurate, demonstrating the feasibility of 3-D US imaging with a vibrating single-element US transducer. [ABSTRACT FROM AUTHOR]

The traditional dynamic models of linear ultrasonic motor (LUSM) do not consider the influences of the preload force and the roughness of the contact surface of stator/slider on the performance of the motor, which unable to effectively describe the dynamic behavior of the motor. In this paper, a dynamic model is established for a V-shaped LUSM considering the influence of the preload force and the roughness of the contact surface of stator/slider on the dynamic behavior of the motor. The contact mechanism of the stator/slider and the influence of preload force on the stator parameters are studied and analyzed. The effectiveness of the developed model is verified by comparing with the analytical model that ignored the effect of the preload force on the stator parameters. The experimental results shown that the developed model can accurately reflect the dynamic characteristics of the motor, and the model will be helpful for the function prediction and precise control of the motor. [ABSTRACT FROM AUTHOR]

Existing 3-D intravascular ultrasound (IVUS) systems that combine two electromagnetic (EM) motors to drive catheters are bulky and require considerable efforts to eliminate EM interference (EMI). Here, we propose a new scanning method to realize 3-D IVUS imaging using a helical ultrasonic motor to overcome the aforementioned issues. The ultrasonic motor with compact dimensions (7-mm outer diameter and 30-mm longitudinal length), lightweight (20.5 g), and free of EMI exhibits a great application potential in mobile imaging devices. In particular, it can simultaneously perform rotary and linear motions, facilitating precise 3-D scanning of an imaging catheter. Experimental results show that the signal-to-noise ratio (SNR) of raw images obtained using the ultrasonic motor is 5.3 dB better than that of an EM motor. Moreover, the proposed imaging device exhibits the maximum rotary speed of 12.3 r/s and the positioning accuracy of 2.6 $\mu \text{m}$ at a driving voltage of 240 Vp-p. The 3-D wire phantom imaging and 3-D tube phantom imaging are performed to evaluate the performance of the imaging device. Finally, the in vitro imaging of a porcine coronary artery demonstrates that the layered architecture of the vessel can be precisely identified while significantly increasing the SNR of the raw images. [ABSTRACT FROM AUTHOR]

This work presents a laminated piezoelectric (PZT) motor to achieve high force density, high strength, and compact structure. The oscillator consists of vibration units and a driving foot. Each of the vibration units is formed by symmetrically bonding two PZT ceramics on a carbon fiber-reinforced plastic (CFRP) layer to improve its strength. The oscillator works in hybrid mode of the first longitudinal vibration (L1) and second bending vibration (B2). The finite-element method is adopted to tune the resonance frequencies of the two modes, and the vibration characteristics are experimentally analyzed. The strength test shows that the presence of the CFRP layer can increase the overall strength of the oscillator by 28% compared with a pure PZT motor. To evaluate the performance, the load characteristics of the fabricated prototype (with a size of 39 × 10 × 4.6 mm3 and weight of 10.6 g) are tested on a designed testbed. The single-phase driving method is used to drive the motor, and the best performance is obtained at the B2-mode frequency. The maximum thrust force, no-load speed, and output power reach 17 N, 335 mm s−1, and 775 mW, respectively, at a drive voltage of 100 Vp. Meanwhile, a thrust density of 1604 N kg−1 and an output power density of 73.11 W kg−1 are achieved. The thrust density is much higher than that of the other motors that operate in the same modes. [ABSTRACT FROM AUTHOR]

Owing to characteristics of single-step fabrication and rapid prototyping, 3D printing have potential applications in processing piezoelectric motors with complex structures. In this paper, a 3D printed resin-based bimodal piezoelectric motor is proposed. Four slots of the motor are designed to reduce the influence of large damping caused by polymer's viscoelastic and enhance mechanical properties. Considering the viscoelasticity and internal structure of the stator, a dynamic model based on the proposed motor is developed. Furthermore, parameters of these slots are optimized using the Taguchi method. Prototypes are fabricated and experimentally investigated. The results demonstrate that the first longitudinal mode and the second bending mode are 17 765 Hz and 18 006 Hz respectively, which are consistent with the analytical model results. Under the voltage of 300 Vpp, the maximum no-load speed and maximum driving load of the slotted motor are 200 r min−1 and 20 g with a speed of 6 r min−1, respectively. Compared with the motor without slots, the speed and load capacity are increased by 25% and 33%. Therefore, the motor with slots exhibits better mechanical output performance. [ABSTRACT FROM AUTHOR]

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively. [ABSTRACT FROM AUTHOR]